This invention relates generally to agricultural balers and more specifically to balers of the traditional rectangular type, i.e. balers which produce bales of crop material which are rectangular in shape. In particular, the invention is concerned with the feeder mechanism of such balers.
In A. Naaktgeboren U.S. Pat. No. 4,525,991, there is disclosed a baler of basically conventional design in that it comprises a bale case or chamber in which a bale of crop material is formed, and which has an inlet opening communicating with a feeder duct or chamber in which charges of crop material are accumulated. After a charge of crop material is accumulated in the feeder duct, it is transferred or stuffed in the bale case for compression by a reciprocable plunger operating therein. In this particular baler, the packing of crop material into the feeder duct to form a charge is effected by packer tines extending along a tine bar rotatable within the feeder duct, and the stuffing of an accumulated charge into the bale case is accomplished by stuffer tines mounted on the tine bar and offset from the packer tines; the outer ends of the respective sets of tines following different paths which are preferably generally apple shaped.
This feeding and stuffing arrangement has been found generally satisfactory except that, with certain crops and crop conditions, the bale case is not always filled evenly across its entire cross section by each charge of crop material from the feeder duct so that bales of uneven density are formed. This is unacceptable to the extent that the uneven density adversely affects the bale shape. Bales of irregular shape and density further also are not well suited for further handling and stacking.
The reason for this incomplete or irregular filling of the bale case cross section with charges of crop material in certain crops and crop conditions can be explained as follows. Considering first the operation of the baler in "normal" crops and crop conditions, it is noted that, as the packer tines of the feeder mechanism pack crop material in the feeder duct to accumulate a charge, this crop material is somewhat compressed during each packing stroke while being advanced in the feeder duct. As soon as the packer tines release the crop material in the feeder duct, said material tends to recover from the compression, i.e. to expand, whereby it engages opposite walls of the feeder duct and thereby remains in the advanced position therein, i.e. it does not tend to fall back towards the inlet of the feeder duct. When finally a full charge is accumulated in the feeder duct, it fills substantially the full length thereof and when subsequently this charge of crop material is stuffed into the bale case it also fills the entire cross section thereof generally evenly as is desired.
Crop material which does not have these springy characteristics behaves itself in a totally different manner during the packing and stuffing cycles of the feeder mechanism. Silage and other crops with a high moisture content do not have this natural resilience. When such crops are being handled, the crop material, which to some extent is compressed by the packer tines as it is fed thereby into the feeder duct, tends not to recover from this compression, whereby it does not maintain its position in the feeder duct when the packer tines retract. Consequently, there is a tendency for a given charge to fall back under gravity once presented to the feeder duct by the packer tines. The greater the time lag between successive tines entering the feeder duct, the further a charge is likely to fall. This problem is aggravated in larger balers which are becoming increasingly popular. This problem also is more critical in so-called "bottom-fed" or "in-line" balers than in the older "side-fed" or "offset" balers for reasons as will be readily appreciated.
When operating in "low volume" crops, the baler according to U.S. Pat. No. 4,525,991 equally may suffer from similar problems as explained hereabove and whereby bales of irregular shape may be formed.
Swenson et al. U.S. Pat. No. 4,275,550 also discloses a baler which generally is of the same type as the baler disclosed in U.S. Pat. No. 4,525,991 to which has been referred hereabove. This baler equally has a feeder duct which communicates with a bale case inlet opening from which it curves downwardly and forwardly to terminate in a forwardly facing open crop receiving mouth. The feeder means equally comprise packer means and stuffer tines. The outermost curved wall (as seen with respect to the radius of curvature of the feeder duct) is resiliently mounted adjacent its lower end to permit outward pivotal movement thereof around a point adjacent the bale case inlet opening when the density of a pre-compressed charge of crop material in the feeder duct exceeds a pre-set value and further crop material still has to be added to this charge before it can be stuffed into the bale case. This arrangement thus enables the accumulation of "larger-than-normal" charges of crop material into the feeder duct without these charges being excessively pre-compressed. However, this arrangement still fails to provide any solution for the above described problems encountered when handling silage or other crop material with a high moisture content.
It is therefore an object of the present invention to overcome or at least attenuate these problems.